From: Andrew Morton <akpm@osdl.org>

Display the most-recently-opened sysfs file's name when oopsing.

From: Adrian Bunk <bunk@stusta.de>

  Build fix

From: Greg Kroah-Hartman <gregkh@suse.de>

  Modified to make the api call cleaner, and available to all arches if
  need be.  Also added it to x86-64's crash dump message.


Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
 arch/i386/kernel/traps.c   |    1 +
 arch/x86_64/kernel/traps.c |    1 +
 fs/sysfs/file.c            |   14 ++++++++++++++
 include/linux/sysfs.h      |    6 ++++++
 4 files changed, 22 insertions(+)

--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -425,6 +425,7 @@ void die(const char * str, struct pt_reg
 #endif
 		if (nl)
 			printk("\n");
+		sysfs_printk_last_file();
 		if (notify_die(DIE_OOPS, str, regs, err,
 					current->thread.trap_no, SIGSEGV) !=
 				NOTIFY_STOP) {
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -533,6 +533,7 @@ void __kprobes __die(const char * str, s
 	printk("DEBUG_PAGEALLOC");
 #endif
 	printk("\n");
+	sysfs_printk_last_file();
 	notify_die(DIE_OOPS, str, regs, err, current->thread.trap_no, SIGSEGV);
 	show_registers(regs);
 	/* Executive summary in case the oops scrolled away */
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -8,6 +8,7 @@
 #include <linux/namei.h>
 #include <linux/poll.h>
 #include <linux/list.h>
+#include <linux/limits.h>
 #include <asm/uaccess.h>
 #include <asm/semaphore.h>
 
@@ -16,6 +17,13 @@
 #define to_subsys(k) container_of(k,struct subsystem,kset.kobj)
 #define to_sattr(a) container_of(a,struct subsys_attribute,attr)
 
+/* used in crash dumps to help with debugging */
+static char last_sysfs_file[PATH_MAX];
+void sysfs_printk_last_file(void)
+{
+	printk(KERN_EMERG "last sysfs file: %s\n", last_sysfs_file);
+}
+
 /*
  * Subsystem file operations.
  * These operations allow subsystems to have files that can be 
@@ -448,6 +456,7 @@ int sysfs_add_file(struct dentry * dir, 
 	umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
 	struct sysfs_dirent *sd;
 	int error = 0;
+	char *p;
 
 	mutex_lock(&dir->d_inode->i_mutex);
 
@@ -464,6 +473,11 @@ int sysfs_add_file(struct dentry * dir, 
 	sd->s_elem.attr.attr = (void *)attr;
 	sysfs_attach_dirent(sd, parent_sd, NULL);
 
+	p = d_path(file->f_dentry, sysfs_mount, last_sysfs_file,
+		   sizeof(last_sysfs_file));
+	if (p)
+		memmove(last_sysfs_file, p, strlen(p) + 1);
+
  out_unlock:
 	mutex_unlock(&dir->d_inode->i_mutex);
 	return error;
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -125,6 +125,7 @@ void sysfs_remove_file_from_group(struct
 		const struct attribute *attr, const char *group);
 
 void sysfs_notify(struct kobject * k, char *dir, char *attr);
+void sysfs_printk_last_file(void);
 
 
 extern int sysfs_make_shadowed_dir(struct kobject *kobj,
@@ -240,6 +241,11 @@ static inline int __must_check sysfs_ini
 	return 0;
 }
 
+static inline void sysfs_printk_last_file(void)
+{
+	;
+}
+
 #endif /* CONFIG_SYSFS */
 
 #endif /* _SYSFS_H_ */